I seem to remember something about magnetic reed switches in security 
systems welding or platting closed after a long period of continues current. 
And I would think that the current was more like less than 10 ma.  The fix 
was to open the contacts occasionally or reverse the current through the 
contacts.  Also, what opens the contacts, the coil or the reeds themselves?

Bill

----- Original Message ----- 
From: "Steven Howes" <steve@poundbury.com>
To: <piclist@mit.edu>
Sent: Friday, May 26, 2006 7:03 AM
Subject: [EE] Reed relay sticking


> Hi, I was wondering if anyone here could work out why a 1A reed relay
> would 'stick' when carrying only 700ma.. It is only a low voltage (ie 2
> or 3 v) so it is unlikely to be a power issue. The reed relay in
> question is an RS Electronics 291-9710. They appear to stick randomly
> then sometimes unstuck which seems a little odd. Is it possible that
> they were damaged during soldering? I have noticed most images of reed
> relays online have them in sockets. Excuse my general stupidity but I
> have had little to do with these little bastar.... Components in the
> past. Thanks in advance for any help.
>
>
>
> Steve Howes
>
> Poundbury Systems Ltd.
>
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